This disclosure relates to polymer composites, and in particular to conductive polymer composites.
Plastic (polymeric resin) is often the material of choice for components in electronic products such as computers, photocopiers, and the like because it offers design flexibility, cost-effective manufacturing, and light weight products. In order to function efficiently in such applications, normally insulating polymeric resin can be made electrically conductive to provide electromagnetic shielding, electrostatic dissipation, or antistatic properties to such components.
Mixing polymeric resins with an electrically conductive material such as graphite powder and/or carbon black powder can increase the electrical and thermal conductivity of a thermoplastic. In U.S. Pat. No. 4,971,726 to Maeno et al. and U.S. Pat. No. 5,846,647 to Makise et al., thermoplastic resins comprising a combination of carbon black and graphite are disclosed. U.S. Pat. No. 5,360,658 to Schmitz et al., Japanese Patent No. JP6041414 to Schmitz et al., and Japanese Patent No. JP2196854 to Toshihiko et al. disclose conductive polycarbonate compositions produced from thermoplastic polycarbonate, polyalkylene terephthalate, and carbon black. Japanese Patent No. JP4146958 discloses conductive compositions comprising a polycarbonate resin, a polybutylene terephthalate resin and/or an acrylic copolymer and carbon black. Due to the high loadings of conductive fillers used in the above-described compositions, a decrease in moldability and degraded mechanical properties, including poor elongation and reduced impact strength, is often observed. There thus remains a need for conductive thermoplastic compositions with enhanced electrical properties without a significant reduction in mechanical properties.